Numerical Simulation Study On Partial Oxidation Of Methane In Atmospheric Pressure Non-equilibrium Plasma

In this paper,hydrogen peroxide vapor is used as oxygen-containing oxidizer to convert methane into methanol.The physicochemical mechanism for partial oxidation of methane to methanol with hydrogen peroxide vapor was simulated.It was proved that atmospheric dielectric barrier discharge?DBD?can be deemed as“reaction carrier”.The two-dimensional axisymmetric fluid model in CH₄/H₂O/H₂O₂ gas mixture is constructed,in which 107 plasma chemical reactions and 28 different species are taken into account.First,spatial and temporal characteristics of main radicals and ions,such as H,CH₃,OH,CH₃OH,CH₃O,CH₂OH,CH₄⁺,CH₃⁺,H₂O₂⁺and H₂O⁺,are presented.It is found that the streamer discharge is sustained by the direct electron-impact ionization of methane molecules.The dominant positive ion flux on to the dielectric surface is methane ion,and its peak value is located at axis.Then,the dominant plasma chemical routes governing the production and loss of CH₃OH and OH are summarized in detail.A schematic overview of dominant reaction pathways for partial oxidation of methane to methanol with hydrogen peroxide vapor is described.Besides,dense methane-air plasma?CH₄:N₂:O₂=45:4:1?discharge is simulated.H,O,CH₃ and CH₂ radicals are deemed as the major radical species production in our dense methane-air plasma discharge.The main reaction paths of their generations and losses are given.The electron-impact dissociations of methane and oxygen are found to be the dominant reaction pathways to produce the major radicals.Three-body recombination reactions are found to be the dominant pathways to consume the major radicals.Moreover,we studied the effect of varying relative permittivity??_r=2,4.5 and9?on the plasma streamer.We find that higher relative permittivity promotes the formation of conduction channel in plasma column.